Barometer.



PATENTED MAY 19, 1908.

B. J UNQUERA. BAROMETER. APPLICATION rum) JAN.17,

W1 Til/E5355 r: ucnms PETERS c0 WASHINGTON, n. c,

PATENT OFFICE.

BUENAVENTURA JUNQUERA, OF OVIEDO, SPAIN.

BAROMETER.

Specification of Letters Patent.

Patented May 19, 1908.

Application filed January 17, 1908. Serial No. 411,250.

T 0 all whom it may concern:

Be it known that I, BUENAVENTURA JUN- QUERA, asubject of the King ofSpain, residing at Campomanes 15, Oviedo, Spain, have invented new anduseful Improvements in Barometers, of which the following is aspecification.

The present invention has for its object the construction of a liquidbarometer which possesses the advantage over the ordinary mercurialbarometer of facilitating the read ing of variations in the atmospherepressure, by means of a special amplifying device. The ordinary columnof mercury is for this purpose combined with a column of a liquid of aless density interposed between the atmosphere and the surface of themercury in the cistern, in such a manner that the atmosphere pressure isactually represented by the weight of the mercury column less the weightof the column of liquid of less density.

It will be understood that if by widening the vacuum chamber of themercury column and the cistern, the variations of the level of themercury column due to the variations of atmospheric pressure arerendered almost inappreciable. The variations in height of the column ofliquid of lesser density will virtually alone represent the variation ofthe atmospheric pressure.

One form of the invention is shown, by way of example, in sectionalelevation, in the annexed drawing.

The barometer comprises a cistern d, into the cap of which therepenetrates, through a fluid-tight joint 9, a mercury tube 6, of whichthe upper part c, forming a vacuum chamber, is suitably widened. Abovethe level I) b of the mercury the cistern is filled with a liquid m ofrelatively smaller density, such for example as water, or preferably anonvolatile liquid (oil, glycerin or the like). The tube 6 enters themercury as in an ordinary barometer, and into the liquid m, passingthrough the cap by means of a fluid-tight joint 7L, there is inserted asecond tube f, which is open to the atmosphere at its upper en Supposingfor example that a liquid is employed, whose density is 1/14th thedensity of mercury, and that it is desired to read variations inpressure of 5 centimeters above and below the mean pressure of 76centimeters, the tube f should have, on either side of a level whichcorresponds to the mean pressure, and which will be marked 76, a heightof 5 X 14: centimeters, that is to say, the total graduated heightshould be 1 meter 40 centimeter. On this column each centimeter ofmercury will be correspondingly represented by 14 centimeters of liquidof lesser density. The readings will consequently be made with immenselygreater facility and accuracy, since it is easy to divide up a column 14centimeters in length, while the fractions of a column of one centimeterlength can only be distinguished with difficulty. It is clear thatprovided that the apparatus is in equilibrium at a mean atmosphericpressure of 76 centimeters, and that the level of the liquid in the tubef is then at the 76 mark, it is necessary that the difference in levelab of the mercury in the chamber 0 and in the cistern d be 76 5 81centimeters. The tube 6 will be constructed accordingly.

In a general way it is necessary for the column of mercury to have atotalheight greater by five centimeters than the mean pressure at theplace where the barometer is used. Supposing that the atmosphericpressure exceeds the mean of 76 by one centimeter for example, theliquid in the tube f will be lowered by 14 centimeters, and will fall tothe 77 division. The liquid driven out of the tube f will pass into thecistern d, and cause a displacement in the level b-b and a flow ofmercury into the chamber 0, and if, for example, the tube f has aninternal diameter of 4 millimeters, thus having in round figures asection of about 12 square millimeters, and that the cistern has adiameter of 200 millimeters equivalent to 30,000 square millimeters insection approximately, an alteration in level of 14 centimeters (ldivision) in the tube f will cause a variation in 12 X 140 30,000 0056millimeters. So that if the pressure changes from 71 to 81 centimetersof mercury the fall in level of the mercury in the cistern d and rise inthe chamber 0 would be 10 times 0.056 millimeters, that is 0.56millimeters. The maximum error is thus but little more than 1 millimeterof mercury, which reprethe level in the cistern of a graduated length of1- m. 40 cm. This can be allowed for in the formation of the scaleengraved on the tube f itself or on a card attached to the apparatus.

The apparatus described above possesses l over mercury barometers theadvantages desents 14 millimeters and this is divided over scribedabove. Over water barometers it possesses the advantage of possessing amercury vacuum chamber which secures a perfeet vacuum. In short theapparatus combines the advantages of both the mercury and waterbarometers without any of the disadvantages of these two Well knowncontrivances.

I claim.

A barometer comprising a closed cistern, containing a heavy liquid suchas mercury, the space between the level of this liquid and the cap beingfilled with a light liquid; a tube closed at its upper end forming avacuum chamber, and inserted at its lower end into the heavy liquid anda tube, open to the atmosphere, inserted into the liquid of lesserdensity; the atmospheric pressure being thus represented by the weightof the column of heavy liquid less the weight of the column of lightliquid.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

BUENAVENTURA JUN QUERA.

Witnesses:

FRANCISCO MUNGUIA, ALBERTO UNRUE.

